--- a/content/base/test/test_child_process_shutdown_message.html
+++ b/content/base/test/test_child_process_shutdown_message.html
@@ -29,17 +29,17 @@ let ppmm = SpecialPowers.Cc["@mozilla.or
  * @param isApp
  *        If true, the example.org site will be loaded as an app.
  */
 function loadBrowser(isApp, callback) {
   let iframe = document.createElement("iframe");
   if (isApp) {
     iframe.setAttribute("mozapp", APP_MANIFEST);
   }
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   iframe.src = APP_URL;
   document.getElementById("content").appendChild(iframe);
 
   iframe.addEventListener("mozbrowserloadend", function onloadend() {
     iframe.removeEventListener("mozbrowserloadend", onloadend);
     callback(iframe);
   });
 }

--- a/content/base/test/test_ipc_messagemanager_blob.html
+++ b/content/base/test/test_ipc_messagemanager_blob.html
@@ -38,17 +38,17 @@
         reader.readAsText(message.json);
       });
     }
 
     function runTests() {
       ok("Browser prefs set.");
 
       let iframe = document.createElement("iframe");
-      iframe.mozbrowser = true;
+      SpecialPowers.wrap(iframe).mozbrowser = true;
       iframe.id = "iframe";
       iframe.src = childFrameURL;
 
       iframe.addEventListener("mozbrowserloadend", function() {
         ok(true, "Got iframe load event.");
 
         const messages = [
           "hi!",

--- a/content/base/test/test_messagemanager_assertpermission.html
+++ b/content/base/test/test_messagemanager_assertpermission.html
@@ -40,17 +40,17 @@ function setUp() {
 }
 
 /**
  * Load the example.org app in an <iframe mozbrowser mozapp>
  */
 function loadApp(callback) {
   let iframe = document.createElement("iframe");
   iframe.setAttribute("mozapp", APP_MANIFEST);
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   iframe.src = APP_URL;
   document.getElementById("content").appendChild(iframe);
 
   iframe.addEventListener("mozbrowserloadend", function onloadend() {
     iframe.removeEventListener("mozbrowserloadend", onloadend);
     callback(iframe);
   });
 }

--- a/dom/browser-element/mochitest/browserElement_Alert.js
+++ b/dom/browser-element/mochitest/browserElement_Alert.js
@@ -10,17 +10,17 @@ var numPendingChildTests = 0;
 var iframe;
 var mm;
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   mm = SpecialPowers.getBrowserFrameMessageManager(iframe);
   mm.addMessageListener('test-success', function(msg) {
     numPendingChildTests--;
     ok(true, SpecialPowers.wrap(msg).json);
   });
   mm.addMessageListener('test-fail', function(msg) {

--- a/dom/browser-element/mochitest/browserElement_AlertInFrame.js
+++ b/dom/browser-element/mochitest/browserElement_AlertInFrame.js
@@ -6,17 +6,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
     is(e.detail.message, 'Hello');
     SimpleTest.finish();
   });
 
   iframe.src = 'file_browserElement_AlertInFrame.html';
   document.body.appendChild(iframe);

--- a/dom/browser-element/mochitest/browserElement_AppFramePermission.js
+++ b/dom/browser-element/mochitest/browserElement_AppFramePermission.js
@@ -21,17 +21,17 @@ function makeAllAppsLaunchable() {
       appRegistry.allAppsLaunchable = originalValue;
     }
   }, false);
 }
 makeAllAppsLaunchable();
 
 function testAppElement(expectAnApp, callback) {
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   iframe.setAttribute('mozapp', 'http://example.org/manifest.webapp');
   iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
     is(e.detail.message == 'app', expectAnApp, e.detail.message);
     SimpleTest.executeSoon(callback);
   });
   document.body.appendChild(iframe);
   iframe.src = 'http://example.org/tests/dom/browser-element/mochitest/file_browserElement_AppFramePermission.html';
 }

--- a/dom/browser-element/mochitest/browserElement_AppWindowNamespace.js
+++ b/dom/browser-element/mochitest/browserElement_AppWindowNamespace.js
@@ -8,30 +8,30 @@ SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
   // Permission to embed an app.
   SpecialPowers.addPermission("embed-apps", true, document);
 
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
   iframe1.setAttribute('mozapp', 'http://example.org/manifest.webapp');
 
   // Two mozapp frames for different apps with the same code both do the same
   // window.open("foo", "bar") call.  We should get two mozbrowseropenwindow
   // events.
 
   iframe1.addEventListener('mozbrowseropenwindow', function(e) {
     ok(true, "Got first mozbrowseropenwindow event.");
     document.body.appendChild(e.detail.frameElement);
 
     SimpleTest.executeSoon(function() {
       var iframe2 = document.createElement('iframe');
-      iframe2.mozbrowser = true;
+      SpecialPowers.wrap(iframe2).mozbrowser = true;
       iframe2.setAttribute('mozapp', 'http://example.com/manifest.webapp');
 
       iframe2.addEventListener('mozbrowseropenwindow', function(e) {
         ok(true, "Got second mozbrowseropenwindow event.");
         SpecialPowers.removePermission("embed-apps", document);
         SimpleTest.finish();
       });
 

--- a/dom/browser-element/mochitest/browserElement_Auth.js
+++ b/dom/browser-element/mochitest/browserElement_Auth.js
@@ -12,17 +12,17 @@ function testFail(msg) {
 
 var iframe;
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   // Wait for the initial load to finish, then navigate the page, then start test
   // by loading SJS with http 401 response.
   iframe.addEventListener('mozbrowserloadend', function loadend() {
     iframe.removeEventListener('mozbrowserloadend', loadend);
     iframe.addEventListener('mozbrowserusernameandpasswordrequired', testHttpAuthCancel);
     SimpleTest.executeSoon(function() {

--- a/dom/browser-element/mochitest/browserElement_BackForward.js
+++ b/dom/browser-element/mochitest/browserElement_BackForward.js
@@ -17,17 +17,17 @@ function addOneShotIframeEventListener(e
   iframe.addEventListener(event, wrapper);
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   addOneShotIframeEventListener('mozbrowserloadend', function() {
     SimpleTest.executeSoon(test2);
   });
 
   iframe.src = browserElementTestHelpers.emptyPage1;
   document.body.appendChild(iframe);
 }

--- a/dom/browser-element/mochitest/browserElement_BadScreenshot.js
+++ b/dom/browser-element/mochitest/browserElement_BadScreenshot.js
@@ -42,17 +42,17 @@ function checkScreenshotResult(expectSuc
   };
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
   iframe.src = 'data:text/html,<html>' +
     '<body style="background:green">hello</body></html>';
 
   iframe.addEventListener('mozbrowserfirstpaint', function() {
     // This one should succeed.
     checkScreenshotResult(true, [100, 100]);
 

--- a/dom/browser-element/mochitest/browserElement_BrowserWindowNamespace.js
+++ b/dom/browser-element/mochitest/browserElement_BrowserWindowNamespace.js
@@ -9,17 +9,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
 
   // Two mozbrowser frames with the same code both do the same
   // window.open("foo", "bar") call.  We should only get one
   // mozbrowseropenwindow event.
 
   iframe1.addEventListener('mozbrowseropenwindow', function(e) {
     ok(true, "Got first mozbrowseropenwindow event.");
     document.body.appendChild(e.detail.frameElement);
@@ -31,17 +31,17 @@ function runTest() {
       }
       else {
         ok(true, "Got locationchange to " + e.detail);
       }
     });
 
     SimpleTest.executeSoon(function() {
       var iframe2 = document.createElement('iframe');
-      iframe2.mozbrowser = true;
+      SpecialPowers.wrap(iframe2).mozbrowser = true;
 
       iframe2.addEventListener('mozbrowseropenwindow', function(e) {
         ok(false, "Got second mozbrowseropenwindow event.");
       });
 
       document.body.appendChild(iframe2);
       iframe2.src = 'file_browserElement_BrowserWindowNamespace.html#2';
     });

--- a/dom/browser-element/mochitest/browserElement_Close.js
+++ b/dom/browser-element/mochitest/browserElement_Close.js
@@ -6,17 +6,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   iframe.addEventListener("mozbrowserclose", function(e) {
     ok(true, "got mozbrowserclose event.");
     SimpleTest.finish();
   });
 
   iframe.src = "data:text/html,<html><body><script>window.close()</scr"+"ipt></body></html>";

--- a/dom/browser-element/mochitest/browserElement_CloseApp.js
+++ b/dom/browser-element/mochitest/browserElement_CloseApp.js
@@ -17,21 +17,21 @@ function runTest() {
   });
 
   // Our app frame and browser frame load the same content.  That content calls
   // window.close() and then alert().  We should get a mozbrowserclose event on
   // the app frame before the mozbrowsershowmodalprompt, but not on the browser
   // frame.
 
   var appFrame = document.createElement('iframe');
-  appFrame.mozbrowser = true;
+  SpecialPowers.wrap(appFrame).mozbrowser = true;
   appFrame.setAttribute('mozapp', 'http://example.org/manifest.webapp');
 
   var browserFrame = document.createElement('iframe');
-  browserFrame.mozbrowser = true;
+  SpecialPowers.wrap(browserFrame).mozbrowser = true;
 
   var gotAppFrameClose = false;
   appFrame.addEventListener('mozbrowserclose', function() {
     ok(true, "Got close from app frame.");
     gotAppFrameClose = true;
   });
 
   var gotAppFrameAlert = false;

--- a/dom/browser-element/mochitest/browserElement_CloseFromOpener.js
+++ b/dom/browser-element/mochitest/browserElement_CloseFromOpener.js
@@ -6,17 +6,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     ok(true, "got openwindow event.");
     document.body.appendChild(e.detail.frameElement);
 
     e.detail.frameElement.addEventListener("mozbrowserclose", function(e) {
       ok(true, "got mozbrowserclose event.");
       SimpleTest.finish();

--- a/dom/browser-element/mochitest/browserElement_ContextmenuEvents.js
+++ b/dom/browser-element/mochitest/browserElement_ContextmenuEvents.js
@@ -29,17 +29,17 @@ var trigger1 = function() {
 };
 
 function runTest() {
 
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
   document.body.appendChild(iframe1);
   iframe1.src = 'data:text/html,<html>' +
     '<body>' +
     '<menu type="context" id="menu1" label="firstmenu">' +
       '<menuitem label="foo" onclick="window.ctxCallbackFired(\'foo\')"></menuitem>' +
       '<menuitem label="bar" onclick="throw(\'anerror\')"></menuitem>' +
     '</menu>' +
     '<menu type="context" id="menu2" label="secondmenu">' +

--- a/dom/browser-element/mochitest/browserElement_CookiesNotThirdParty.js
+++ b/dom/browser-element/mochitest/browserElement_CookiesNotThirdParty.js
@@ -9,17 +9,17 @@ SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   const innerPage = 'http://example.com/tests/dom/browser-element/mochitest/file_browserElement_CookiesNotThirdParty.html';
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
     if (e.detail.message == 'next') {
       iframe.src = innerPage + '?step=2';
       return;
     }
 
     if (e.detail.message.startsWith('success:')) {

--- a/dom/browser-element/mochitest/browserElement_DOMRequestError.js
+++ b/dom/browser-element/mochitest/browserElement_DOMRequestError.js
@@ -7,17 +7,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
   iframe1.src = 'data:text/html,<html>' +
     '<body style="background:green">hello</body></html>';
   document.body.appendChild(iframe1);
 
   function testIframe(beforeRun, isErrorExpected, nextTest) {
     return function() {
       var error = false;
       if (beforeRun)

--- a/dom/browser-element/mochitest/browserElement_DataURI.js
+++ b/dom/browser-element/mochitest/browserElement_DataURI.js
@@ -6,17 +6,17 @@
 "use strict";
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
   iframe1.id = 'iframe1';
   iframe1.addEventListener('mozbrowserloadend', function if1_loadend() {
     iframe1.removeEventListener('mozbrowserloadend', if1_loadend);
     ok(true, 'Got first loadend event.');
     SimpleTest.executeSoon(runTest2);
   });
   iframe1.src = browserElementTestHelpers.emptyPage1;
   document.body.appendChild(iframe1);

--- a/dom/browser-element/mochitest/browserElement_DocumentFirstPaint.js
+++ b/dom/browser-element/mochitest/browserElement_DocumentFirstPaint.js
@@ -57,14 +57,14 @@ function testFirstLoad() {
   iframe.src = browserElementTestHelpers.emptyPage1;
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   runTestQueue([testFirstLoad, testReload, testChangeLocation]);
 }
 
 runTest();

--- a/dom/browser-element/mochitest/browserElement_ErrorSecurity.js
+++ b/dom/browser-element/mochitest/browserElement_ErrorSecurity.js
@@ -7,17 +7,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener("mozbrowsererror", function(e) {
     ok(true, "Got mozbrowsererror event.");
     ok(e.detail.type, "Event's detail has a |type| param.");
     SimpleTest.finish();
   });
 
   iframe.src = "https://expired.example.com";

--- a/dom/browser-element/mochitest/browserElement_ExposableURI.js
+++ b/dom/browser-element/mochitest/browserElement_ExposableURI.js
@@ -44,14 +44,14 @@ function testWyciwyg() {
   iframe.addEventListener('mozbrowserlocationchange', locationchange);
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
   testWyciwyg();
 }
 
 addEventListener('load', function() { SimpleTest.executeSoon(runTest); });

--- a/dom/browser-element/mochitest/browserElement_FirstPaint.js
+++ b/dom/browser-element/mochitest/browserElement_FirstPaint.js
@@ -6,17 +6,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   var gotFirstPaint = false;
   var gotFirstLocationChange = false;
   iframe.addEventListener('mozbrowserfirstpaint', function(e) {
     ok(!gotFirstPaint, "Got only one first paint.");
     gotFirstPaint = true;
 
     if (gotFirstLocationChange) {

--- a/dom/browser-element/mochitest/browserElement_ForwardName.js
+++ b/dom/browser-element/mochitest/browserElement_ForwardName.js
@@ -8,17 +8,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   iframe.setAttribute('name', 'foo');
 
   iframe.addEventListener("mozbrowseropenwindow", function(e) {
     ok(false, 'Got mozbrowseropenwindow, but should not have.');
   });
 
   iframe.addEventListener('mozbrowserlocationchange', function(e) {
     ok(true, "Got locationchange to " + e.detail);

--- a/dom/browser-element/mochitest/browserElement_FrameWrongURI.js
+++ b/dom/browser-element/mochitest/browserElement_FrameWrongURI.js
@@ -6,31 +6,31 @@
 "use strict";
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframeJS = document.createElement('iframe');
-  iframeJS.mozbrowser = true;
+  SpecialPowers.wrap(iframeJS).mozbrowser = true;
 
   iframeJS.addEventListener('mozbrowserloadstart', function(e) {
     ok(false, "This should not happen!");
   });
 
   iframeJS.addEventListener('mozbrowserloadend', function(e) {
     ok(false, "This should not happen!");
   });
 
   iframeJS.src = 'javascript:alert("Foo");';
   document.body.appendChild(iframeJS);
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   var gotPopup = false;
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     is(gotPopup, false, 'Should get just one popup.');
     gotPopup = true;
 
     document.body.appendChild(e.detail.frameElement);
   });

--- a/dom/browser-element/mochitest/browserElement_GetScreenshot.js
+++ b/dom/browser-element/mochitest/browserElement_GetScreenshot.js
@@ -7,17 +7,17 @@
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
 
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
   document.body.appendChild(iframe1);
   iframe1.src = 'data:text/html,<html>' +
     '<body style="background:green">hello</body></html>';
 
   var screenshotArrayBuffers = [];
   var numLoaded = 0;
 
   function screenshotTaken(screenshotArrayBuffer) {

--- a/dom/browser-element/mochitest/browserElement_Iconchange.js
+++ b/dom/browser-element/mochitest/browserElement_Iconchange.js
@@ -14,24 +14,24 @@ function createLink(name) {
   return '<link rel="icon" type="image/png" href="http://example.com/' + name + '.png">';
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
   document.body.appendChild(iframe1);
 
   // iframe2 is a red herring; we modify its favicon but don't listen for
   // iconchanges; we want to make sure that its iconchange events aren't
   // picked up by the listener on iframe1.
   var iframe2 = document.createElement('iframe');
-  iframe2.mozbrowser = true;
+  SpecialPowers.wrap(iframe2).mozbrowser = true;
   document.body.appendChild(iframe2);
 
   // iframe3 is another red herring.  It's not a mozbrowser, so we shouldn't
   // get any iconchange events on it.
   var iframe3 = document.createElement('iframe');
   document.body.appendChild(iframe3);
 
   var numIconChanges = 0;

--- a/dom/browser-element/mochitest/browserElement_KeyEvents.js
+++ b/dom/browser-element/mochitest/browserElement_KeyEvents.js
@@ -18,17 +18,17 @@ let whitelistedEvents = [
 
 SimpleTest.waitForExplicitFinish();
 
 browserElementTestHelpers.setEnabledPref(true);
 browserElementTestHelpers.addPermission();
 browserElementTestHelpers.setOOPDisabledPref(true); // this is breaking the autofocus.
 
 var iframe = document.createElement('iframe');
-iframe.mozbrowser = true;
+SpecialPowers.wrap(iframe).mozbrowser = true;
 iframe.src = browserElementTestHelpers.focusPage;
 document.body.appendChild(iframe);
 
 // Number of expected events at which point we will consider the test as done.
 var nbEvents = whitelistedEvents.length * 3;
 
 function eventHandler(e) {
   ok(((e.type == 'keydown' || e.type == 'keypress' || e.type == 'keyup') &&

--- a/dom/browser-element/mochitest/browserElement_LoadEvents.js
+++ b/dom/browser-element/mochitest/browserElement_LoadEvents.js
@@ -16,17 +16,17 @@ function runTest() {
   //
   // This should trigger loadstart, locationchange, and loadend events.
 
   var seenLoadEnd = false;
   var seenLoadStart = false;
   var seenLocationChange = false;
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   iframe.id = 'iframe';
   iframe.src = browserElementTestHelpers.emptyPage1;
 
   function loadstart(e) {
     ok(e.isTrusted, 'Event should be trusted.');
     ok(!seenLoadEnd, 'loadstart before loadend.');
     ok(!seenLoadStart, 'Just one loadstart event.');
     ok(!seenLocationChange, 'loadstart before locationchange.');

--- a/dom/browser-element/mochitest/browserElement_NextPaint.js
+++ b/dom/browser-element/mochitest/browserElement_NextPaint.js
@@ -6,17 +6,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   // Add a first listener that we'll remove shortly after.
   iframe.addNextPaintListener(wrongListener);
 
   var gotFirstNextPaintEvent = false;
   iframe.addNextPaintListener(function () {
     ok(!gotFirstNextPaintEvent, 'got the first nextpaint event');

--- a/dom/browser-element/mochitest/browserElement_OpenMixedProcess.js
+++ b/dom/browser-element/mochitest/browserElement_OpenMixedProcess.js
@@ -24,17 +24,17 @@ function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   // We're going to open a remote frame if OOP off by default.  If OOP is on by
   // default, we're going to open an in-process frame.
   var remote = !browserElementTestHelpers.getOOPByDefaultPref();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   iframe.setAttribute('remote', remote);
 
   // The page we load does window.open, then checks some things and reports
   // back using alert().  Finally, it calls alert('finish').
   //
   // Bug 776129 in particular manifests itself such that the popup frame loads
   // and the tests in file_browserElement_OpenMixedProcess pass, but the
   // content of the frame is invisible.  To catch this case, we take a

--- a/dom/browser-element/mochitest/browserElement_OpenNamed.js
+++ b/dom/browser-element/mochitest/browserElement_OpenNamed.js
@@ -9,17 +9,17 @@ SimpleTest.waitForExplicitFinish();
 
 var iframe;
 var popupFrame;
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   var gotPopup = false;
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     is(gotPopup, false, 'Should get just one popup.');
     gotPopup = true;
     popupFrame = e.detail.frameElement;
     is(popupFrame.getAttribute('name'), 'OpenNamed');
 

--- a/dom/browser-element/mochitest/browserElement_OpenWindow.js
+++ b/dom/browser-element/mochitest/browserElement_OpenWindow.js
@@ -6,17 +6,17 @@
 "use strict";
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   var gotPopup = false;
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     is(gotPopup, false, 'Should get just one popup.');
     gotPopup = true;
 
     document.body.appendChild(e.detail.frameElement);
 

--- a/dom/browser-element/mochitest/browserElement_OpenWindowDifferentOrigin.js
+++ b/dom/browser-element/mochitest/browserElement_OpenWindowDifferentOrigin.js
@@ -6,17 +6,17 @@
 "use strict";
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     ok(true, 'Got first window.open call');
 
     e.detail.frameElement.addEventListener('mozbrowseropenwindow', function(e) {
       ok(true, 'Got second window.open call');
       document.body.appendChild(e.detail.frameElement);
     });

--- a/dom/browser-element/mochitest/browserElement_OpenWindowInFrame.js
+++ b/dom/browser-element/mochitest/browserElement_OpenWindowInFrame.js
@@ -12,17 +12,17 @@
 "use strict";
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   var gotPopup = false;
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     is(gotPopup, false, 'Should get just one popup.');
     gotPopup = true;
 
     document.body.appendChild(e.detail.frameElement);
 

--- a/dom/browser-element/mochitest/browserElement_OpenWindowRejected.js
+++ b/dom/browser-element/mochitest/browserElement_OpenWindowRejected.js
@@ -7,17 +7,17 @@
 "use strict";
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     ok(e.detail.url.indexOf('does_not_exist.html') != -1,
        'Opened URL; got ' + e.detail.url);
     is(e.detail.name, '');
     is(e.detail.features, '');
 
     // Don't add e.detail.frameElement to the DOM, so the window.open is

--- a/dom/browser-element/mochitest/browserElement_OpenWindowRejected2.js
+++ b/dom/browser-element/mochitest/browserElement_OpenWindowRejected2.js
@@ -11,17 +11,17 @@
 "use strict";
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     ok(e.detail.url.indexOf('does_not_exist.html') != -1,
        'Opened URL; got ' + e.detail.url);
     is(e.detail.name, '');
     is(e.detail.features, '');
 
     // Call preventDefault, but don't add the iframe to the DOM.  This still

--- a/dom/browser-element/mochitest/browserElement_PromptCheck.js
+++ b/dom/browser-element/mochitest/browserElement_PromptCheck.js
@@ -21,17 +21,17 @@ var oldDialogTimeLimitPref;
 try {
   oldDialogTimeLimitPref = SpecialPowers.getIntPref(dialogTimeLimitPrefName);
 }
 catch(e) {}
 
 SpecialPowers.setIntPref(dialogTimeLimitPrefName, 10);
 
 var iframe = document.createElement('iframe');
-iframe.mozbrowser = true;
+SpecialPowers.wrap(iframe).mozbrowser = true;
 document.body.appendChild(iframe);
 
 var numPrompts = 0;
 iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
   is(e.detail.message, numPrompts, "prompt message");
   if (numPrompts / 10 < 1) {
     is(e.detail.promptType, 'alert');
   }

--- a/dom/browser-element/mochitest/browserElement_PromptConfirm.js
+++ b/dom/browser-element/mochitest/browserElement_PromptConfirm.js
@@ -10,17 +10,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   var prompts = [
     {msg: 1, type: 'alert', rv: 42, expected: 'undefined'},
     {msg: 2, type: 'confirm', rv: true, expected: 'true'},
     {msg: 3, type: 'confirm', rv: false, expected: 'false'},
 
     // rv == 42 should be coerced to 'true' for confirm.

--- a/dom/browser-element/mochitest/browserElement_PurgeHistory.js
+++ b/dom/browser-element/mochitest/browserElement_PurgeHistory.js
@@ -17,17 +17,17 @@ function addOneShotIframeEventListener(e
   iframe.addEventListener(event, wrapper);
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   addOneShotIframeEventListener('mozbrowserloadend', function() {
     SimpleTest.executeSoon(test2);
   });
 
   iframe.src = browserElementTestHelpers.emptyPage1;
   document.body.appendChild(iframe);
 }

--- a/dom/browser-element/mochitest/browserElement_Reload.js
+++ b/dom/browser-element/mochitest/browserElement_Reload.js
@@ -17,17 +17,17 @@ var iframe;
 var loadedEvents = 0;
 var countAcc;
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowserloadend', mozbrowserLoaded);
 
   iframe.src = 'file_bug741717.sjs';
   document.body.appendChild(iframe);
 }
 
 function iframeBodyRecv(data) {

--- a/dom/browser-element/mochitest/browserElement_ReloadPostRequest.js
+++ b/dom/browser-element/mochitest/browserElement_ReloadPostRequest.js
@@ -71,17 +71,17 @@ function pageLoadDone() {
   iframe.reload();
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   isPostRequestSubmitted = false;
   iframe.src = 'file_post_request.html';
   document.body.appendChild(iframe);
 
   iframe.addEventListener('mozbrowserloadend', pageLoadDone);
 
   let expectedMessage = getExpectedStrings();

--- a/dom/browser-element/mochitest/browserElement_RemoveBrowserElement.js
+++ b/dom/browser-element/mochitest/browserElement_RemoveBrowserElement.js
@@ -8,17 +8,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   iframe.addEventListener("mozbrowsershowmodalprompt", function(e) {
     document.body.removeChild(iframe);
     SimpleTest.executeSoon(function() {
       ok(true);
       SimpleTest.finish();
     });

--- a/dom/browser-element/mochitest/browserElement_ScrollEvent.js
+++ b/dom/browser-element/mochitest/browserElement_ScrollEvent.js
@@ -6,17 +6,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   iframe.addEventListener("mozbrowserscroll", function(e) {
     ok(true, "got mozbrowserscroll event.");
     ok(e.detail, "event.detail is not null.");
     ok(e.detail.top === 4000, "top position is correct.");
     ok(e.detail.left === 4000, "left position is correct.");
     SimpleTest.finish();

--- a/dom/browser-element/mochitest/browserElement_SecurityChange.js
+++ b/dom/browser-element/mochitest/browserElement_SecurityChange.js
@@ -7,17 +7,17 @@
 "use strict";
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   var lastSecurityState;
   iframe.addEventListener('mozbrowsersecuritychange', function(e) {
     lastSecurityState = e.detail;
   });
 
   var filepath = 'tests/dom/browser-element/mochitest/file_browserElement_SecurityChange.html';
 

--- a/dom/browser-element/mochitest/browserElement_SendEvent.js
+++ b/dom/browser-element/mochitest/browserElement_SendEvent.js
@@ -6,17 +6,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement("iframe");
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   iframe.addEventListener("mozbrowserloadend", function onloadend(e) {
     iframe.sendMouseEvent("mousedown", 10, 10, 0, 1, 0);
   });
 
   iframe.addEventListener("mozbrowserlocationchange", function onlocchange(e) {
     var a = document.createElement("a");

--- a/dom/browser-element/mochitest/browserElement_SetVisible.js
+++ b/dom/browser-element/mochitest/browserElement_SetVisible.js
@@ -17,17 +17,17 @@ var iframeScript = function() {
 function runTest() {
 
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var mm;
   var numEvents = 0;
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
   iframe1.src = 'data:text/html,1';
 
   document.body.appendChild(iframe1);
 
   function recvVisibilityChanged(msg) {
     msg = SpecialPowers.wrap(msg);
     numEvents++;
     if (numEvents === 1) {

--- a/dom/browser-element/mochitest/browserElement_SetVisibleFrames.js
+++ b/dom/browser-element/mochitest/browserElement_SetVisibleFrames.js
@@ -19,17 +19,17 @@ function runTest() {
   browserElementTestHelpers.addPermission();
 
   var principal = SpecialPowers.wrap(SpecialPowers.getNodePrincipal(document));
   SpecialPowers.addPermission("browser", true, { url: SpecialPowers.wrap(principal.URI).spec,
                                                  appId: principal.appId,
                                                  isInBrowserElement: true });
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   // Our test involves three <iframe mozbrowser>'s, parent, child1, and child2.
   // child1 and child2 are contained inside parent.  child1 is visibile, and
   // child2 is not.
   //
   // For the purposes of this test, we want there to be a process barrier
   // between child{1,2} and parent.  Therefore parent must be a non-remote
   // <iframe mozbrowser>, until bug 761935 is resolved and we can have nested

--- a/dom/browser-element/mochitest/browserElement_SetVisibleFrames2.js
+++ b/dom/browser-element/mochitest/browserElement_SetVisibleFrames2.js
@@ -13,17 +13,17 @@ function runTest() {
   browserElementTestHelpers.addPermission();
 
   var principal = SpecialPowers.wrap(SpecialPowers.getNodePrincipal(document));
   SpecialPowers.addPermission("browser", true, { url: SpecialPowers.wrap(principal.URI).spec,
                                                  appId: principal.appId,
                                                  isInBrowserElement: true });
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   // We need remote = false here until bug 761935 is fixed; see
   // SetVisibleFrames.js for an explanation.
   iframe.remote = false;
 
   iframe.addEventListener('mozbrowserloadend', function loadEnd(e) {
     iframe.removeEventListener('mozbrowserloadend', loadEnd);
     iframe.setVisible(false);

--- a/dom/browser-element/mochitest/browserElement_Stop.js
+++ b/dom/browser-element/mochitest/browserElement_Stop.js
@@ -15,17 +15,17 @@ var iframe;
 var stopped = false;
 var imgSrc = 'http://test/tests/dom/browser-element/mochitest/file_bug709759.sjs';
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowserloadend', loadend);
   iframe.src = 'data:text/html,<html>' +
     '<body><img src="' + imgSrc + '" /></body></html>';
 
   document.body.appendChild(iframe);
 
   setTimeout(function() {

--- a/dom/browser-element/mochitest/browserElement_TargetBlank.js
+++ b/dom/browser-element/mochitest/browserElement_TargetBlank.js
@@ -7,17 +7,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     is(e.detail.url, 'http://example.com/');
     SimpleTest.finish();
   });
 
   iframe.src = "file_browserElement_TargetBlank.html";
   document.body.appendChild(iframe);

--- a/dom/browser-element/mochitest/browserElement_TargetTop.js
+++ b/dom/browser-element/mochitest/browserElement_TargetTop.js
@@ -7,17 +7,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   iframe.addEventListener('mozbrowseropenwindow', function(e) {
     ok(false, 'Not expecting an openwindow event.');
   });
 
   iframe.addEventListener('mozbrowserlocationchange', function(e) {
     if (/file_browserElement_TargetTop.html\?2$/.test(e.detail)) {
       ok(true, 'Got the locationchange we were looking for.');

--- a/dom/browser-element/mochitest/browserElement_Titlechange.js
+++ b/dom/browser-element/mochitest/browserElement_Titlechange.js
@@ -6,24 +6,24 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe1 = document.createElement('iframe');
-  iframe1.mozbrowser = true;
+  SpecialPowers.wrap(iframe1).mozbrowser = true;
   document.body.appendChild(iframe1);
 
   // iframe2 is a red herring; we modify its title but don't listen for
   // titlechanges; we want to make sure that its titlechange events aren't
   // picked up by the listener on iframe1.
   var iframe2 = document.createElement('iframe');
-  iframe2.mozbrowser = true;
+  SpecialPowers.wrap(iframe2).mozbrowser = true;
   document.body.appendChild(iframe2);
 
   // iframe3 is another red herring.  It's not a mozbrowser, so we shouldn't
   // get any titlechange events on it.
   var iframe3 = document.createElement('iframe');
   document.body.appendChild(iframe3);
 
   var numTitleChanges = 0;

--- a/dom/browser-element/mochitest/browserElement_TopBarrier.js
+++ b/dom/browser-element/mochitest/browserElement_TopBarrier.js
@@ -12,17 +12,17 @@ function runTest() {
   iframe = document.createElement('iframe');
   iframe.addEventListener('mozbrowserloadend', function() {
     try {
       outerIframeLoaded();
     } catch(e) {
       dump("Got error: " + e + '\n');
     }
   });
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   iframe.src = 'data:text/html,Outer iframe <iframe id="inner-iframe"></iframe>';
   // For kicks, this test uses a display:none iframe.  This shouldn't make a
   // difference in anything.
   iframe.style.display = 'none';
   document.body.appendChild(iframe);
 
   SimpleTest.waitForExplicitFinish();
 }

--- a/dom/browser-element/mochitest/browserElement_XFrameOptions.js
+++ b/dom/browser-element/mochitest/browserElement_XFrameOptions.js
@@ -7,17 +7,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   // The page we load will fire an alert when it successfully loads.
   iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
     ok(true, "Got alert");
     SimpleTest.finish();
   });
 
   document.body.appendChild(iframe);

--- a/dom/browser-element/mochitest/browserElement_XFrameOptionsAllowFrom.js
+++ b/dom/browser-element/mochitest/browserElement_XFrameOptionsAllowFrom.js
@@ -25,17 +25,17 @@ function arrayBuffersEqual(a, b) {
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
   var count = 0;
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   iframe.height = '1000px';
 
   // The innermost page we load will fire an alert when it successfully loads.
   iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
     switch (e.detail.message) {
     case 'step 1':
       // Make the page wait for us to unblock it (which we do after we finish
       // taking the screenshot).

--- a/dom/browser-element/mochitest/browserElement_XFrameOptionsDeny.js
+++ b/dom/browser-element/mochitest/browserElement_XFrameOptionsDeny.js
@@ -25,17 +25,17 @@ function arrayBuffersEqual(a, b) {
   return true;
 }
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   // Our child will create two iframes, so make sure this iframe is big enough
   // to show both of them without scrolling, so taking a screenshot gets both
   // frames.
   iframe.height = '1000px';
 
   iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
     switch (e.detail.message) {

--- a/dom/browser-element/mochitest/browserElement_XFrameOptionsSameOrigin.js
+++ b/dom/browser-element/mochitest/browserElement_XFrameOptionsSameOrigin.js
@@ -9,17 +9,17 @@
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermission();
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
 
   // The innermost page we load will fire an alert when it successfully loads.
   iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
     ok(true, "Got alert");
     SimpleTest.finish();
   });
 
   document.body.appendChild(iframe);

--- a/dom/browser-element/mochitest/createNewTest.py
+++ b/dom/browser-element/mochitest/createNewTest.py
@@ -36,17 +36,17 @@ js_template = textwrap.dedent("""\
 
     SimpleTest.waitForExplicitFinish();
 
     function runTest() {{
       browserElementTestHelpers.setEnabledPref(true);
       browserElementTestHelpers.addPermission();
 
       var iframe = document.createElement('iframe');
-      iframe.mozbrowser = true;
+      SpecialPowers.wrap(iframe).mozbrowser = true;
 
       // FILL IN TEST
 
       document.body.appendChild(iframe);
     }}
 
     runTest();""")
 

--- a/dom/browser-element/mochitest/file_browserElement_SetVisibleFrames2_Outer.html
+++ b/dom/browser-element/mochitest/file_browserElement_SetVisibleFrames2_Outer.html
@@ -1,14 +1,14 @@
 <html>
 <body>
 <script>
 
 var iframe = document.createElement('iframe');
-iframe.mozbrowser = true;
+iframe.setAttribute("mozbrowser", "true");
 
 iframe.addEventListener('mozbrowsershowmodalprompt', function(e) {
   if (e.detail.message == 'child:ready') {
     setTimeout(function() {
       iframe.setVisible(false);
       iframe.setVisible(true);
       setTimeout(function() {
         alert('parent:finish');

--- a/dom/browser-element/mochitest/file_browserElement_SetVisibleFrames_Outer.html
+++ b/dom/browser-element/mochitest/file_browserElement_SetVisibleFrames_Outer.html
@@ -22,21 +22,21 @@ function handlePrompt(e) {
     alert('parent:ready');
   }
   else if (numPrompts == 4 || numPrompts == 5) {
     alert(e.detail.message);
   }
 }
 
 var iframe1 = document.createElement('iframe');
-iframe1.mozbrowser = true;
+iframe1.setAttribute("mozbrowser", "true");
 iframe1.addEventListener('mozbrowsershowmodalprompt', handlePrompt);
 
 var iframe2 = document.createElement('iframe');
-iframe2.mozbrowser = true;
+iframe2.setAttribute("mozbrowser", "true");
 iframe2.addEventListener('mozbrowsershowmodalprompt', handlePrompt);
 
 iframe1.src = 'file_browserElement_SetVisibleFrames_Inner.html?child1';
 iframe2.src = 'file_browserElement_SetVisibleFrames_Inner.html?child2';
 document.body.appendChild(iframe1);
 document.body.appendChild(iframe2);
 
 </script>

--- a/dom/browser-element/mochitest/test_browserElement_NoPref.html
+++ b/dom/browser-element/mochitest/test_browserElement_NoPref.html
@@ -21,17 +21,17 @@ https://bugzilla.mozilla.org/show_bug.cg
 "use strict";
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(false);
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   iframe.addEventListener('mozbrowserloadstart', function() {
     ok(false, 'Should not send mozbrowserloadstart event.');
   });
 
   iframe.addEventListener('load', function() {
     ok(true, 'Got iframe load event.');

--- a/dom/browser-element/mochitest/test_browserElement_NoWhitelist.html
+++ b/dom/browser-element/mochitest/test_browserElement_NoWhitelist.html
@@ -22,17 +22,17 @@ https://bugzilla.mozilla.org/show_bug.cg
 
 SimpleTest.waitForExplicitFinish();
 
 function runTest() {
   browserElementTestHelpers.setEnabledPref(true);
   browserElementTestHelpers.addPermissionForUrl('http://foobar.com');
 
   var iframe = document.createElement('iframe');
-  iframe.mozbrowser = true;
+  SpecialPowers.wrap(iframe).mozbrowser = true;
   document.body.appendChild(iframe);
 
   iframe.addEventListener('mozbrowserloadstart', function() {
     ok(false, 'Should not send mozbrowserloadstart event.');
   });
 
   iframe.addEventListener('load', function() {
     ok(true, 'Got iframe load event.');

--- a/dom/devicestorage/ipc/test_ipc.html
+++ b/dom/devicestorage/ipc/test_ipc.html
@@ -84,17 +84,17 @@
       mm.removeMessageListener("test:DeviceStorage:ipcTestMessage", onTestMessage);
       mm.removeMessageListener("test:DeviceStorage:ipcTestComplete", onTestComplete);
 
       SimpleTest.executeSoon(function () { SimpleTest.finish(); });
     }
 
     function runTests() {
       let iframe = document.createElement("iframe");
-      iframe.mozbrowser = true;
+      SpecialPowers.wrap(iframe).mozbrowser = true;
       iframe.id = "iframe";
       iframe.style.width = "100%";
       iframe.style.height = "1000px";
 
       function iframeLoadSecond() {
         ok(true, "Got second iframe load event.");
         iframe.removeEventListener("mozbrowserloadend", iframeLoadSecond);
         let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);

--- a/dom/indexedDB/ipc/test_ipc.html
+++ b/dom/indexedDB/ipc/test_ipc.html
@@ -103,17 +103,17 @@
       is(usingChildProcess, true, "Expecting to run in child process");
       is(seenTestMessage, true, "Expecting to receive messages from child");
       SpecialPowers.removePermission("browser", window.location.href);
       SimpleTest.executeSoon(function () { SimpleTest.finish(); });
     }
 
     function runTests() {
       let iframe = document.createElement("iframe");
-      iframe.mozbrowser = true;
+      SpecialPowers.wrap(iframe).mozbrowser = true;
       iframe.id = "iframe";
       iframe.style.width = "100%";
       iframe.style.height = "1000px";
 
       function iframeLoadSecond() {
         ok(true, "Got second iframe load event.");
         iframe.removeEventListener("mozbrowserloadend", iframeLoadSecond);
         let mm = SpecialPowers.getBrowserFrameMessageManager(iframe);

--- a/layout/base/tests/test_remote_frame.html
+++ b/layout/base/tests/test_remote_frame.html
@@ -38,17 +38,17 @@
         todo(false, "We couldn't draw the frame, but at least we didn't crash");
         SimpleTest.finish();
         return;
       }
       setTimeout(pollForTestPass, 10);
     }
     function addRemoteFrame() {
       let iframe = document.createElement("iframe");
-      iframe.mozbrowser = true;
+      SpecialPowers.wrap(iframe).mozbrowser = true;
       iframe.src = "data:text/html,<html style='background:blue;'>";
 
       document.body.appendChild(iframe);
 
       pollForTestPass();
     }
     addEventListener("load", function() {
       referenceSnapshot = snapshotWindow(window);